Treatment of oils to reduce viscosity and sulfur content



C. J. ENGLE Feb. 17, 1970 TREATMENT 0F OILS T0 REDUCE VISCOSITY AND sULFURNTENT Filed Jan. 17, 1968 United States Patent O M U.S. Cl. 208-208 1 Claim ABSTRACT OF THE DISCLOSURE The viscosity and sulfur content of an oil is reduced by maintaining the oil at an elevated temperature for an eX- tended period of time. Gases evolved from the oil are separated, the lighter portion being used as fuel to heat the oil and the heavier portion being blended with the treated oil for further viscosity reduction.

This invention relates to the treatment of oils to reduce the viscosity and the sulfur content thereof.

A number of oil fields have been discovered which contain oils having high viscosities. The transportation of these oils is often quite diiicult, particularly when the oils are found in remote locations. In order to transport the oils through pipelines, it has often been necessary to blend in substantial quantities of lighter oils or to resort to rening operations adjacent the oil producing elds. These methods have substantially increased the cost of recovering the oils and have not always been entirely satisfactory. In addition, many of the viscous crude oils have an undesirably high sulfur content. This is particularly serious when the oils are to be used for fuel purposes in populated areas. In order to meet customer specifications and governmental regulations, it is often necessary to install rather expensive treating facilities to reduce the sulfur content.

ln accordance with the present invention, a simple, inexpensive method is provided for reducing the viscosity of oils and for lowering the sulfur content. This is accomplished by heating the oil to a temperature in the general range of 500 to 700 F. and maintaining the oil at such a temperature for a period of at least 24 hours, preferably longer. The gases evolved during this heating step are cooled and separated to produce fuel gas and condensate. The latter is blended with the heated oil to reduce its viscosity still further and provide a material that can be transported more readily. The fuel gas is utilized to heat the oil to be treated, thereby eliminating or Substantially reducing the fuel requirements of the treating process and utilizing the gases which are evolved from the treating step.

Accordingly, it is an object of this invention to provide an improved method for reducing the viscosity of oil and for simultaneously reducing the sulfur content.

Another object is to provide novel apparatus for use in treating oil.

Other objects, advantages and features of the invention should become apparent from the following detailed description, taken in conjunction with the accompanying drawing which is a schematic representation of apparatus employed to carry out the method of this invention.

Referring now to the drawing in detail, there is shown a relatively large storage vessel which is provided with a heat insulated jacket 11. A crude oil to be treated is introduced through a conduit 12 which communicates with the inlet of salt and water removal apparatus 13. This apparatus, which can be of the type described in U.S. Patent 3,165,466, for example, can be employed when the crude oil contains excessive amounts of salt. The treated oil removed from apparatus 13 is conveyed through a conduit 14 to the inlet of a heater 15. Heater 3,496,097 Patented Feb. 17, 1970 ICC 15 is provided with burners 16 which receive fuel from a conduit 17. The heated oil is removed from heater 15 through a conduit 18 and introduced into vessel 10. Oil is subsequently removed from vessel 10 through an outlet conduit 20 which has a control valve 21 therein.

Heater 15 is designed to elevate the temperature of oil to a valve in the general range of 500 to 700 F. Vessel 10 is of suicient size to produce a desired average residence time of the oil therein. This average residence time is at least 24 hours, and generally will not be more than about 3 weeks. For example, if oil is supplied through conduit 42 at a rate of 10,000 barrels per day and an aver.

age residence time of ten days is desired, vessel 10 should have a volume of 100,000 barrels. It is preferred that the oil be maintained in vessel 10 for an average residence time of the order of one to two weeks. The oil should be maintained in the temperature range of 500 to 700 F. during the time that it is retained in vessel 10. If necessary to maintain the desired temperature, a portion of the oil can be removed through a conduit 22, which has a control valve 23 therein, and recirculated to the inlet of heater 15. lf desired, heater 15 can be an integral part of storage vessel 10 to supply heat directly to the stored oil. The treated oil removed through outlet conduit 20 has a substantially lower viscosity than the inlet oil, and has a lower sulfur content. It is desirable to maintain an inert atmosphere in the vapor space above the oil in vessel 10. This can be accomplished by introducing an inert gas through a conduit 25, which has a control valve 26 therein. The inert gas can be circulated through the vapor space and removed through an outlet conduit 27 which has a controlvalve 28 therein. This inert gas can be introduced in sufficient volume to elevate the pressure within the treating vessel. In normal operation, valves 26 and 28 can be closed after an initial purge has taken place.

A substantial volume of gas is evolved from the oil during the treating operation. This gas is conveyed through a conduit 27A, which has a condenser 28A and an expansion valve 29 therein, to the inlet of a flash chamber 30. The lighter gases are removed as vapor from the top of the ash chamber through a conduit 31 which communicates with the inlet of a compressor 32. The higher boiling constituents, which normally are C4 and heavier hydrocarbons, are removed through a conduit 30' which communicates with oil outlet conduit 20. These heavier hydrocarbons are thus blended with the treated oil to reduce further the viscosity of the treated oil.

The compressed gases from compressor 32 are conveyed by a conduit 33 to the inlet of a scrubber 34, which can be a column having packing material therein. An aqueous absorbing agent, such as water, is introduced into the top of scrubber 34 through a conduit 35 to remove hydrogen sulfide which may be contained in the gaS stream. The effluent gas from scrubber 34 is removed through a conduit 36. A conduit 37, which has a control valve 38 therein, communicates between conduit 36 and conduit 17 to direct effluent gas from scrubber 34 to heater 15. In the event that a greater quantity of gas is produced than is needed in heater 15, excess gas can be removed through a conduit 40 which has a control valve 41 therein. In the event that the volume of recovered gas is not suiiicient to supply the heat required to elevate the oil to the desired temperature, additional fuel can be introduced through a conduit 42 which has a control valve 43 therein. 1f heater 15 is provided with burners of proper configuration, a portion of the crude oil can be utilized as additional fuel, if required.

The water having hydrogen sulfide dissolved therein is removed from scrubber 34 through a conduit 45 which communicates with a stripper 46. Stripper 46 is provided with a heater 47 to elevate the temperature and thereby strip out the entrained hydrogen sulfide Which is removed through an overhead conduit 48. Water is removed from stripper 46 through a conduit 49 which communicates with conduit 35, the latter having a cooler 50 therein. Make-up water is introduced, as required, through a conduit S1 which has a control valve 52 therein. The hydrogen sulfide removed from stripper 46 can be conveyed to a sulfur producing unit.

The illustrated apparatus has been shown schematically to simplify the drawing and explanation of the invention. For this reason, various pumps and control elements normally employed have been omitted.

Operating features of this invention are demonstrated by the following runs which were conducted on samples of crude oil obtained from the Morichal Field, Monagas, Venezuela. Two samples were employed which had the following properties:

122 F. cp. Weight percent Sample No viscosity Gravity, AP sulfur What is claimed is:

1. The method of treating an oil to reduce its viscosity and its sulfur content comprising:

heating said oil to a temperature in the range of S00 to maintaining said oil at a temperature in said range in a storage zone for an average residence time of from about 24 hours to about 3 Weeks;

removing gases evolved from said oil in said storage zone;

O separating said gases into a first portion comprising 25 removing said oil from said storage, and combining said first portion with said oil removed from said storage oils after the heating step. zone.

Run No 1 2 3 4 5 6 7 8 9 1o Charge:

Sample No 1 1 2 2 2 2 2 2 2 2 Oil, g 336 369 1, 94o 1, 940 1, 940 1, 040 1, 040 1, 940 1, 940 339 Ware 50 6 50 60 60 60 60 60 10 Reaction conditions:

Time, hours 336 336 25. 5 49, 5 73. 5 121. 5 169. 5 217. 5 313 336 Temperature, iff-average- 543 605 604 598 602 600 595 595 597 605 Average pressure, p.s.1 1, 780 2, 1, 270 725 690 610 610 610 590 14 7 Produced oil properties:

Gravity, API 14 15.3 9. 5 10.4 10.0 10. 5 10 9 11.7 12 2 10 s 122 F. viscosity, op 360 4, 320 2, 955 1, 940 385 614 446 236 505 Sulfur, weight pereent l. 6 1. 7 4. l 4.0 3 9 3.9 3. 7 3. 5 3. 0 3. 1 Sulfur, removed, percent 23 19 0 2. 5 5 0 5. 0 10.0 15 0 25.0 24. 5 Produced gas, N 2, free basis: Volume produced,

ee., NTP 134 2, 710 6, 720

The compositions of the produced gases were as follows References Cited the total reduced as from Runs 3 to 9 bein 6650 ce. p g g UNITED STATES PATENTS Run No' (Volume Percent) 45 1,018,040 2/ 1912 Eggleston 208-208 component 1 2 3-0 (total) 1o 1,018,374 2/1912 Robinson 208-208 5 7 5 7 5 1 1,592,324 7/ 1926 Allinson 208-177 es 38.0 32.3 3,119,764 l/1964 Cabbage 208-208 8'8 ig 0.03 0,7 1 2 5 DELBERT E. GANTZ, Prlmary Examiner 3.5 3.8 8.o 0 6 0.3 5.4 G. J. CRASANAKIS, Assistant Examiner 

